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Wireless communication with the help of Wi-Fi and Bluetooth has created an explosive impact on the society. It allows everyone to use internet without getting tangled with wires. Both Wi-Fi and Bluetooth make use of radio waves for the communication purpose. Radio waves facilitate these with not-so-bad speeds but the transmission of data is slow. And also radio waves get affected by other equipment like ovens. To this scenario, Prof. Harald Haas and his team of University of Edinburgh, UK, have introduced a method to transfer data with the help of LED lights, that is, Li-Fi or Light Fidelity. In Wi-Fi, radio waves are transmitted around an area from the wireless router. The transmitted waves are detected by the wireless device which connects to internet via the router. This method is used in Li-Fi also, where light is used for transmission, that is, LED lights move around you carrying data with varying intensities. An important advantage of Li-Fi over Wi-Fi is that, it is un-interrupted by equipment emitting radio waves.
It is a form of communication that is supposed to use the light that is being emitted by the Light Emitting Diodes (LEDs) as a medium to provide high speed communication. This is a variant of Visible Light Communication (VLC) which uses visible light in the electromagnetic spectrum. The LEDs are switched on and off which indicates data transfer within nanoseconds without the human eye gets noticed.
Electromagnetic spectrum is shown below. Radio waves spectrum is becoming insufficient for the increasing demand. Infrared is currently used for low-power applications. Visible light spectrum is not currently used and Li-Fi is on the path of using visible light spectrum to change the data transmission scenario. Ultraviolet rays are generally categorized as rays harmful to human bodies. X-rays are widely used in hospital for diagnosis. Gamma rays are not generally used.
White LED lights are used to implement this technology which is present at the downlink transmitter. By applying a constant current these LED lights can be used for illumination. And depending upon the variations of current, the light output undergoes variation at high speeds. This is the setup basically used in Li-Fi. When the LED is ON it transmits 1 and in case, it is OFF, then 0 is transmitted. Due to the faster switching speeds of LEDs, the chances of transmitting data is very high. The circuitry for data transmission through light essentially requires LED lights and a controller, which can code data into the LEDs followed by flickering of LED light depending upon the data to be transmitted.
A setup that has been implemented to showcase the Light-Fidelity technology is given below. Here the data that is originated from server and internet modulates the LED lamp light intensity which is normally imperceptible to the human eye. As LEDs are semiconductor devices, the modulated current and the output is detected by a photo-detector. The photo-detector device converts light energy back to electrical energy. This is then converted into data streams and further transmitted to mobiles, laptops etc. High Speed Communication is possible with this technology with ease. Researches have achieved a transmission rate of 10GBps data rate. Thus LED bulbs can light up a room as well as carry out data transmission without any harmful side effects.
Radio spectrum is becoming endangered depending upon the increasing demand. The issues regarding the radio spectrum is capacity, efficiency, safety and security which is actually the main features under Li-Fi technology.
The bandwidth of visible spectrum is 10,000 more than the radio frequency spectrum and is absolutely untouched and free to use. The data density of this technology is 100 times better than Wi-Fi as light is less prone to interference or spreading out when compared RF waves. High intensity light output, greater bandwidths and low interference provides high speed data rates.
The components requirement for this technology is very less when compared to RF technology and thus it is a low cost technology. The data transmission via LED light requires less power making it energy efficient. Li-Fi working is very much environmental friendly when compared to RF technology that is actually not propagated in water.
There is no question of health or safety concerns related to this technology. Radio frequencies generally interfere with other electronic circuitry which makes it non-hazardous to the environment
Li-Fi signals are less interpreted as the signals are confined within an illumination area that is a closed network and does not travel through the walls. Sometimes user can see the data transfer so make the transmission under control.
The table below shows a comparison of Li-Fi with Wi-Fi over certain parameters.
The cellular networks that demand for excess capacity can be moved to Li-Fi networks wherever it is available. This is of more use in case of downlink rather than uplink as bottlenecks occur more in downlink process. Lighting arrangements, whether public or private, can be used as a Li-Fi hotspot and the same arrangement can be used for the monitoring and control of lighting and data. Li-Fi can help mobiles, laptops and PDAs to interconnect directly. Data rates provided by Li-Fi are very high and it offers higher security. Electromagnetic interference is not emitted by Li-Fi and thus it interferes less with medical instruments such as MRI scanners. Health hazards for this technology is less when compared with RF waves. Underwater communications for short range is possible with Li-Fi but RF use for this case is impractical as signals are absorbed in water. In a traffic island, LED lights of vehicles transfer data between other vehicles, so accidents can be avoided. In Aircraft, In-Flight Entertainment can be connected with mobile by using this rich technology
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